Pseudo-first-order phase transition for ultrahigh positive/negative electrocaloric effects in perovskite ferroelectrics

Two types of pseudo-first-order phase transition (PFOPT) coexist in ferroelectric materials, which occur at temperatures lower than the paraelectric/ferroelectric transition Curie temperature. Ultrahigh positive and negative electrocaloric effects are associated with the PFOPTs which could fully utilized an applied electric field during its loading and unloading.